Hi aditya,
some comments on the other bog item ... (others may wikify it)
you can do a quick and dirty solution as well (tested in mkiv):
\def\MoleculeC#1{$\enablesupersub\tf#1$}
now, concerning the lua solution, it looks pretty clean and ok, but
there is some room for improvement ... the following version supports
nested braces and numbers (we can let this evolve in a proper chemical
subsystem if needed since eventually i will replace ppchtex anyway)
\startluacode
local molecule = { }
local format, sprint = string.format, tex.sprint
function commands.justtext(one)
sprint(tex.ctxcatcodes,one)
end
function commands.low(str)
sprint(tex.ctxcatcodes,format("\\low{%s}",str))
end
function commands.high(str)
sprint(tex.ctxcatcodes,format("\\high{%s}",str))
end
function commands.lowhigh(one,two)
sprint(tex.ctxcatcodes,format("\\lohi{%s}{%s}",one,two))
end
function commands.highlow(one,two)
sprint(tex.ctxcatcodes,format("\\hilo{%s}{%s}",one,two))
end
local lowercase = lpeg.R("az")
local uppercase = lpeg.R("AZ")
local plus = lpeg.P("+")
local minus = lpeg.P("-")
local digit = lpeg.R("09")
local sign = plus + minus
local cardinal = digit^1
local integer = sign^0 * cardinal
local leftbrace = lpeg.P("{")
local rightbrace = lpeg.P("}")
local nobrace = 1 - (leftbrace + rightbrace)
local nested = lpeg.P { leftbrace * (nobrace + lpeg.V(1))^0 *
rightbrace }
local any = lpeg.P(1)
local subscript = lpeg.P("_")
local superscript = lpeg.P("^")
local content = lpeg.C(nested + integer + any)
-- could be made more efficient
local lowhigh = subscript * content * superscript * content /
commands.lowhigh
local highlow = superscript * content * subscript * content /
commands.highlow
local low = subscript * content /
commands.low
local high = superscript * content /
commands.high
local justtext = lpeg.C((1 - somescript)^1) /
commands.justtext
local parser = (sometext + lowhigh + highlow + low + high)^0
function commands.molecule(string)
parser:match(string)
end
\stopluacode
\def\molecule#1{\ctxlua{commands.molecule("#1")}}
\molecule{H_2SO_4^-2}
\molecule{H_2SO_4^{-2}}
\molecule{H_2SO_4^{-2{x}}}
Hans
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